xref: /petsc/src/mat/impls/sbaij/seq/sbaijfact3.c (revision 6849ba73f22fecb8f92ef896a42e4e8bd4cd6965)
1 
2 #include "src/mat/impls/sbaij/seq/sbaij.h"
3 #include "src/inline/ilu.h"
4 
5 /* Version for when blocks are 3 by 3  */
6 #undef __FUNCT__
7 #define __FUNCT__ "MatCholeskyFactorNumeric_SeqSBAIJ_3"
8 PetscErrorCode MatCholeskyFactorNumeric_SeqSBAIJ_3(Mat A,Mat *B)
9 {
10   Mat                C = *B;
11   Mat_SeqSBAIJ       *a = (Mat_SeqSBAIJ*)A->data,*b = (Mat_SeqSBAIJ *)C->data;
12   IS                 perm = b->row;
13   PetscErrorCode ierr;
14   int                *perm_ptr,i,j,mbs=a->mbs,*bi=b->i,*bj=b->j;
15   int                *ai,*aj,*a2anew,k,k1,jmin,jmax,*jl,*il,vj,nexti,ili;
16   MatScalar          *ba = b->a,*aa,*ap,*dk,*uik;
17   MatScalar          *u,*diag,*rtmp,*rtmp_ptr;
18 
19   PetscFunctionBegin;
20 
21   /* initialization */
22   ierr = PetscMalloc(9*mbs*sizeof(MatScalar),&rtmp);CHKERRQ(ierr);
23   ierr = PetscMemzero(rtmp,9*mbs*sizeof(MatScalar));CHKERRQ(ierr);
24   ierr = PetscMalloc(2*mbs*sizeof(int),&il);CHKERRQ(ierr);
25   jl   = il + mbs;
26   for (i=0; i<mbs; i++) {
27     jl[i] = mbs; il[0] = 0;
28   }
29   ierr = PetscMalloc(18*sizeof(MatScalar),&dk);CHKERRQ(ierr);
30   uik  = dk + 9;
31   ierr = ISGetIndices(perm,&perm_ptr);CHKERRQ(ierr);
32 
33   /* check permutation */
34   if (!a->permute){
35     ai = a->i; aj = a->j; aa = a->a;
36   } else {
37     ai   = a->inew; aj = a->jnew;
38     ierr = PetscMalloc(9*ai[mbs]*sizeof(MatScalar),&aa);CHKERRQ(ierr);
39     ierr = PetscMemcpy(aa,a->a,9*ai[mbs]*sizeof(MatScalar));CHKERRQ(ierr);
40     ierr = PetscMalloc(ai[mbs]*sizeof(int),&a2anew);CHKERRQ(ierr);
41     ierr = PetscMemcpy(a2anew,a->a2anew,(ai[mbs])*sizeof(int));CHKERRQ(ierr);
42 
43     for (i=0; i<mbs; i++){
44       jmin = ai[i]; jmax = ai[i+1];
45       for (j=jmin; j<jmax; j++){
46         while (a2anew[j] != j){
47           k = a2anew[j]; a2anew[j] = a2anew[k]; a2anew[k] = k;
48           for (k1=0; k1<9; k1++){
49             dk[k1]       = aa[k*9+k1];
50             aa[k*9+k1] = aa[j*9+k1];
51             aa[j*9+k1] = dk[k1];
52           }
53         }
54         /* transform columnoriented blocks that lie in the lower triangle to roworiented blocks */
55         if (i > aj[j]){
56           /* printf("change orientation, row: %d, col: %d\n",i,aj[j]); */
57           ap = aa + j*9;                     /* ptr to the beginning of j-th block of aa */
58           for (k=0; k<9; k++) dk[k] = ap[k]; /* dk <- j-th block of aa */
59           for (k=0; k<3; k++){               /* j-th block of aa <- dk^T */
60             for (k1=0; k1<3; k1++) *ap++ = dk[k + 3*k1];
61           }
62         }
63       }
64     }
65     ierr = PetscFree(a2anew);CHKERRQ(ierr);
66   }
67 
68   /* for each row k */
69   for (k = 0; k<mbs; k++){
70 
71     /*initialize k-th row with elements nonzero in row perm(k) of A */
72     jmin = ai[perm_ptr[k]]; jmax = ai[perm_ptr[k]+1];
73     if (jmin < jmax) {
74       ap = aa + jmin*9;
75       for (j = jmin; j < jmax; j++){
76         vj = perm_ptr[aj[j]];         /* block col. index */
77         rtmp_ptr = rtmp + vj*9;
78         for (i=0; i<9; i++) *rtmp_ptr++ = *ap++;
79       }
80     }
81 
82     /* modify k-th row by adding in those rows i with U(i,k) != 0 */
83     ierr = PetscMemcpy(dk,rtmp+k*9,9*sizeof(MatScalar));CHKERRQ(ierr);
84     i = jl[k]; /* first row to be added to k_th row  */
85 
86     while (i < mbs){
87       nexti = jl[i]; /* next row to be added to k_th row */
88 
89       /* compute multiplier */
90       ili = il[i];  /* index of first nonzero element in U(i,k:bms-1) */
91 
92       /* uik = -inv(Di)*U_bar(i,k) */
93       diag = ba + i*9;
94       u    = ba + ili*9;
95 
96       uik[0] = -(diag[0]*u[0] + diag[3]*u[1] + diag[6]*u[2]);
97       uik[1] = -(diag[1]*u[0] + diag[4]*u[1] + diag[7]*u[2]);
98       uik[2] = -(diag[2]*u[0] + diag[5]*u[1] + diag[8]*u[2]);
99 
100       uik[3] = -(diag[0]*u[3] + diag[3]*u[4] + diag[6]*u[5]);
101       uik[4] = -(diag[1]*u[3] + diag[4]*u[4] + diag[7]*u[5]);
102       uik[5] = -(diag[2]*u[3] + diag[5]*u[4] + diag[8]*u[5]);
103 
104       uik[6] = -(diag[0]*u[6] + diag[3]*u[7] + diag[6]*u[8]);
105       uik[7] = -(diag[1]*u[6] + diag[4]*u[7] + diag[7]*u[8]);
106       uik[8] = -(diag[2]*u[6] + diag[5]*u[7] + diag[8]*u[8]);
107 
108       /* update D(k) += -U(i,k)^T * U_bar(i,k) */
109       dk[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2];
110       dk[1] += uik[3]*u[0] + uik[4]*u[1] + uik[5]*u[2];
111       dk[2] += uik[6]*u[0] + uik[7]*u[1] + uik[8]*u[2];
112 
113       dk[3] += uik[0]*u[3] + uik[1]*u[4] + uik[2]*u[5];
114       dk[4] += uik[3]*u[3] + uik[4]*u[4] + uik[5]*u[5];
115       dk[5] += uik[6]*u[3] + uik[7]*u[4] + uik[8]*u[5];
116 
117       dk[6] += uik[0]*u[6] + uik[1]*u[7] + uik[2]*u[8];
118       dk[7] += uik[3]*u[6] + uik[4]*u[7] + uik[5]*u[8];
119       dk[8] += uik[6]*u[6] + uik[7]*u[7] + uik[8]*u[8];
120 
121       /* update -U(i,k) */
122       ierr = PetscMemcpy(ba+ili*9,uik,9*sizeof(MatScalar));CHKERRQ(ierr);
123 
124       /* add multiple of row i to k-th row ... */
125       jmin = ili + 1; jmax = bi[i+1];
126       if (jmin < jmax){
127         for (j=jmin; j<jmax; j++) {
128           /* rtmp += -U(i,k)^T * U_bar(i,j) */
129           rtmp_ptr = rtmp + bj[j]*9;
130           u = ba + j*9;
131           rtmp_ptr[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2];
132           rtmp_ptr[1] += uik[3]*u[0] + uik[4]*u[1] + uik[5]*u[2];
133           rtmp_ptr[2] += uik[6]*u[0] + uik[7]*u[1] + uik[8]*u[2];
134 
135           rtmp_ptr[3] += uik[0]*u[3] + uik[1]*u[4] + uik[2]*u[5];
136           rtmp_ptr[4] += uik[3]*u[3] + uik[4]*u[4] + uik[5]*u[5];
137           rtmp_ptr[5] += uik[6]*u[3] + uik[7]*u[4] + uik[8]*u[5];
138 
139           rtmp_ptr[6] += uik[0]*u[6] + uik[1]*u[7] + uik[2]*u[8];
140           rtmp_ptr[7] += uik[3]*u[6] + uik[4]*u[7] + uik[5]*u[8];
141           rtmp_ptr[8] += uik[6]*u[6] + uik[7]*u[7] + uik[8]*u[8];
142         }
143 
144         /* ... add i to row list for next nonzero entry */
145         il[i] = jmin;             /* update il(i) in column k+1, ... mbs-1 */
146         j     = bj[jmin];
147         jl[i] = jl[j]; jl[j] = i; /* update jl */
148       }
149       i = nexti;
150     }
151 
152     /* save nonzero entries in k-th row of U ... */
153 
154     /* invert diagonal block */
155     diag = ba+k*9;
156     ierr = PetscMemcpy(diag,dk,9*sizeof(MatScalar));CHKERRQ(ierr);
157     ierr = Kernel_A_gets_inverse_A_3(diag);CHKERRQ(ierr);
158 
159     jmin = bi[k]; jmax = bi[k+1];
160     if (jmin < jmax) {
161       for (j=jmin; j<jmax; j++){
162          vj = bj[j];           /* block col. index of U */
163          u   = ba + j*9;
164          rtmp_ptr = rtmp + vj*9;
165          for (k1=0; k1<9; k1++){
166            *u++        = *rtmp_ptr;
167            *rtmp_ptr++ = 0.0;
168          }
169       }
170 
171       /* ... add k to row list for first nonzero entry in k-th row */
172       il[k] = jmin;
173       i     = bj[jmin];
174       jl[k] = jl[i]; jl[i] = k;
175     }
176   }
177 
178   ierr = PetscFree(rtmp);CHKERRQ(ierr);
179   ierr = PetscFree(il);CHKERRQ(ierr);
180   ierr = PetscFree(dk);CHKERRQ(ierr);
181   if (a->permute){
182     ierr = PetscFree(aa);CHKERRQ(ierr);
183   }
184 
185   ierr = ISRestoreIndices(perm,&perm_ptr);CHKERRQ(ierr);
186   C->factor    = FACTOR_CHOLESKY;
187   C->assembled = PETSC_TRUE;
188   C->preallocated = PETSC_TRUE;
189   PetscLogFlops(1.3333*27*b->mbs); /* from inverting diagonal blocks */
190   PetscFunctionReturn(0);
191 }
192